User blog comment:Meshifuari Arimota/Devil May Cry V/@comment-33329977-20180608154444/@comment-33329977-20180608170610

Nero's "signature" is that arm, I don't think it would be wise to take that mechanics out of his arsenal.

But Vergil being inside him might indicate that maybe his role in history is to help Nero in some way, maybe even training him on how to use the Yamato properly